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The simulation of block or random ethylene oxide (EO) and propylene oxide (PO) copolymerization with a deterministic model requires the solution of many thousands of differential and algebraic equations. This approach, therefore, is not practicable, requiring too long computer calculation time. The use of a stochastic model allows overcoming this drawback. In this work, a Monte Carlo based model has been developed considering, for a given substrate such as ethylene glycol, only the reaction of the overall consumption of the alkoxides. The addition of new units of EO or PO, respectively, to the hydroxyls of the substrate or the terminal hydroxyls of the growing chains is ruled by the stochastic probability of the two mentioned events. The developed model considers also the effect of the side reaction of PO conversion to allyl alcohol with the formation of new growing polymeric chains. To do the calculations a microscopic volume, assumed to be a well-mixed system, is considered containing about 5000 or a few more molecules, which is a number significant for statistical validity. Kinetic laws and related parameters have been estimated from data published in the literature. Examples of simulations of high-molecular-weight EO and PO homopolymers, of an EO-PO random copolymer, and a triblocks copolymer of the type (EO)a-(PO)b-(EO)a will be presented.

A rigorous mathematical model was developed for a complex liquid–liquid–solid system in a batch reactor. The approach is general but well applicable for the indirect epoxidation of vegetable oils according to the concept of Nikolaj Prileschajew, implying in situ prepared percarboxylic acids as epoxidation agents. The model considers intra- and interfacial mass transfer effects coupled to reaction kinetics. The liquid phases were described with chemical approach (aqueous phase) and a reaction–diffusion approach (oil phase). The oil droplets were treated as rigid spheres, in which the overall reaction rate is influenced by chemical reactions and molecular diffusion. The model was tested with a generic example, where two reactions proceeded simultaneously in the aqueous and oil phases. The example (i.e., fatty acid epoxidation) illustrated the power of real multiphase model in epoxidation processes. The proposed modeling concept can be used for optimization purposes for applications, which comprise a complex water–oil–solid catalyst system.

The study and the understanding of the importance of the morphological properties of heterogeneous catalysts can pave the way for important improvements in the performance of catalytic systems. Non-uniform active phase distribution catalysts are normally adopted for consecutive reactions to improve the selectivity to the desired intermediate product. Attributes on which minor attention is paid, such as the distribution and thickness of the active phase, can be decisive in the final rationale of the catalyst synthesis strategy. Starting from a previous work, where a single non-uniform active phase model for catalyst particles was developed, a key step to control the entire system is to include the bulk-phase equations and related transport phenomena. For this purpose, this work proposes a modeling approach of a biphasic reactive system in a batch reactor in the presence of three different kinds of catalytic particles (egg shell, egg white, and egg yolk) whose distinction lies in the localization of the active zone. The reactive network consists of a couple of reactions in series, which take place exclusively on the solid surface, and the intermediate component is the main product of interest. To reveal the influence related to the type of catalyst, an extensive parametric study was conducted, varying several structural coefficients to highlight the changes in the intraparticle and bulk concentration profiles of the different chemical species. The main results can be considered of wide interest for the chemical reaction engineering community, as it was demonstrated that mass and heat transfer limitations affect the catalyst performance. For the chosen system, the egg shell catalyst normally led to better catalytic performances.

Nonanoic acid is obtained as main coproduct in the synthesis of azelaic acid from oleic acid. The increase of azelaic acid production, being a monomer useful to synthesize biodegradable polyesters, lead to a high availability of nonanoic acid, that can be used as feedstock in esterification reactions to obtain lubricants and solvents. In this work, the esterification of nonanoic acid with 2-ethylhexanol to produce a solvent were conducted in a batch reactor in the presence of either a homogeneous (H2SO4) or an heterogenous catalyst (Amberlite IR120). The intrinsic reaction kinetics was investigated by considering all the physical and chemical phenomena occurring in the reaction network, leading to the determination of thermodynamic and kinetic parameters. The activation energy values of both catalysts are similar (≈60 kJ/mol) and the enthalpy value of ΔrH = 10.3 kJ/mol showed that the reaction is slightly endothermic. The reaction is shifted to the products as demonstrated by the reference equilibrium constant equal to 1.69 at 333 K. The obtained results will be useful to design industrial reactors.

In recent years, the use of renewable raw materials for the production of chemicals has been the subject of different studies. In particular, the interest of the present study was the use of oleins, mixtures of free fatty acids (FFAs), and oleic acid to produce bio-based components for lubricants formulations and the investigation of the performance of a styrene-divinylbenzene acid resin (sPSB-SA) in the esterification reaction of fatty acids. This resin has shown good activity as a heterogeneous catalyst and high stability at elevated temperatures (180 °C). It was tested in the esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol. In particular, the esterification reactions were performed in a steel stirred batch reactor and a PBR loop reactor. Tests were conducted varying the reaction conditions, such as alcohol type, temperature, reaction time, and catalysts, both homogeneous and heterogeneous ones. From the obtained results, acid resin (both in reticulated and not-reticulated form) showed high activity in esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol and good resistance to the deactivation, thus, they can be considered promising candidates for future applications in continuous devices. Viscosity tests were performed, underlining the good properties of the obtained products as lubricant bases.

Linseed oil is characterized by an elevated concentration of highly unsaturated fatty acids such as linolenic and linoleic acids. This work has the objective to evaluate the effect of the high unsaturation of linseed oil on the reactivity and selectivity of the epoxidation reaction. For this purpose, different kinetic experiments of linseed oil epoxidation with performic acid, produced in situ, and phosphoric acid as catalyst, have been performed and interpreted with a biphasic kinetic model previously tested on soybean oil epoxidation. This model considers the contribution of the main reactions involved in each phase, including the side reactions such as performic acid decomposition and ring opening reactions. The experiments made have been simulated, with the mentioned kinetic model, after the evaluation by mathematical regression of the kinetic and thermodynamic parameters of the model. Then, the obtained results have been compared with those described in the literature for soybean seed oil, considering, in particular, the effect of the different unsaturated fatty acids composition on activity and selectivity.

The kinetics of formation and decomposition of peroxyformic acid was studied. From experimental evidences taken from literature, we noticed the decomposition reaction depends on the source of the hydrogen peroxide used as a reactant, so we focused on the idea that stabilizing agents present in the hydrogen peroxide solutions affect the reaction rate, inhibiting the peracid decomposition. The nature of the stabilizing agents and the concentration used might in fact change from a supplier to another. A kinetic model was proposed, in which the decomposition model takes into account this effect and, as a first approximation, the stabilizing agent concentration is quantified indirectly through the initial concentration of hydrogen peroxide loaded in the reactive system. The present model aims to lay the foundations for a new approach to the study of the decomposition of peracids in reactive systems.

To maximize the performances of heterogeneous catalytic reactors, it is necessary to consider many parameters. Catalytic particle morphology (dimension, shape, active phase distribution) is generally previously established and seldom considered in the optimization of the catalyst to be specific for a given process. In this work, the influence of active phase distribution within spherical catalytic particles (egg-shell, egg-yolk and egg-white), on the yield and selectivity of a product is shown for a consecutive reaction network, here, the intermediate component is the main product of interest. Intraparticle mass and energy balances under non-steady conditions were implemented. Sensitivity studies lead to the identification of the optimal conditions, thus maximizing the yield of the intermediate for each active phase distribution. It was demonstrated that the egg-shell catalyst can maximize the intermediate yield, with a lower active-phase usage.

Levulinic acid and its esters are considered very versatile chemical compounds used for a wide range of derivatives. Traditionally ethyl levulinate is synthesized in batch reactors, using homogeneous catalysts (H2SO4, H3PO4). Several investigations were reported on solid acid catalysts, as zeolites, sulfated oxides, sulfonic ion-exchange resins. Amberlyst-15 showed high potentials: to design a continuous reactor, it is necessary to investigate the stability of the catalyst and the kinetics of the reaction. In the present work, we demonstrated that the resin is stable for more than 5 days. Kinetic and mass transfer phenomena were studied, evaluating the partition and take-up of the used resin when put in contact with reactants and products. Two different samples of Amberlyst-15 were used, characterized by different size, demonstrating that bigger particles lead to higher intraparticle diffusion limitations.

In this work, the kinetics of soybean oil epoxidation with hydrogen peroxide in the presence of formic acid as an oxygen carrier and phosphoric acid as a catalyst has been studied. A biphasic kinetic model developed in a previous work has been improved considering the evolution of four different reactions with time: (1) the oxidation of formic acid to performic acid, occurring in aqueous phase; (2) the epoxidation reaction, occurring in oil phase; (3) the ring-opening reaction, mainly occurring at the liquid-liquid interface; and (4) the performic acid decomposition, occurring in aqueous phase. The kinetics of reactions 1, 3, and 4 have been studied in an independent way, and the best kinetic parameters found and published elsewhere have been used for interpreting the experimental results obtained in performing reaction 2. A kinetic law for this reaction has been proposed, and the related best-fitting parameters have been determined.

International audience; Levulinic acid (LA) is one of the most important platform chemicals as it is a versatile building block for a variety of high value-added products, fine chemicals and pharmaceutical intermediates. Catalytic esterification of LA with alkyl alcohols leads to levulinate esters which can be used as fragrances, flavoring agents and fuel additives. In the present work, the kinetics of the levulinic acid esterification with ethanol in the presence of Amberlite IR120 was investigated in a batch reactor. The collected experimental data were interpreted with a reliable model taking into account also for the mass transfer phenomena involved in the reaction network. The kinetic model was further validated by conducting experiments in a fixed bed reactor. The reactor was characterized in terms of fluid-dynamics and the collected kinetic data were interpreted with a reliable reactor model, considering the extent of the reaction and fluid-solid mass transfer limitation.

A continuous hydrogen peroxide propene oxide (HPPO) lab-scale pilot plant was designed and tested for the production of propene oxide via HPPO process. The plant was equipped with a continuous stirred tank reactor, able to work under nitrogen pressure with liquid propene. Attention was paid to the feed system and the plant control, the lab-scale pilot plant being completely automated. Hydraulic tests were performed to check the performance of the plant; a fluid-dynamic characterization was conducted to evaluate the residence time distribution. Propene oxide synthesis experiments were performed to evaluate both hydrogen peroxide conversion and propene oxide selectivity. The collected data were interpreted with a recently published kinetics, validating the developed model, obtaining satisfactory results, also in simulating the start-up transient state of the reactor. The model can be considered of high utility in designing and optimizing HPPO process, to achieve high reactant conversions and propene oxide yields.

The growing availability of glycerol, as a consequence of the increase in biodiesel production (for which glycerol is a byproduct), is rapidly saturating the market, and consequently, a great interest is now addressed to the development of new process routes for alternative uses of glycerol. Among the various possibilities, our attention has been focused on the glycerol chlorination reaction, with the aim to produce dichlorohydrin. This compound can then subsequently be converted into epichlorohydrin, which is an important intermediate in the production of epoxy resins. dicholorhydrin, together with R,â-dichlorohydrin, is currently synthesized starting from propylene via allyl chloride. In the present paper, the kinetics of glycerol chlorination with gaseous hydrochloric acid, for the production of dichlorohydrin, has been investigated by means of a jacketed glass reactor operated in batch conditions for the substrate (glycerol) and continuously for the hydrochloric acid. Different organic acids have been tested as catalysts with good performances in terms of both activity and, in particular, selectivity toward the desired 1,3-dichlorinated product. A reaction mechanism has been proposed and a consequent kinetic model has been developed in order to quantitatively describe the experimental data collected at various temperatures (80-120 °C), and the kinetic parameters have been evaluated. A generally good agreement between the experimental data and the theoretical model has been found.